The present invention relates generally to electronic timers, and specifically to an electronic timer which activates a household appliance at a preset time of day.
For automatic activation of household appliances such as coffee makers, electronic cycle timers have been used which generate an activation signal at a preset time each day. Such an electronic timer basically consists of an integrated circuit which is manufactured in high volume and is used in digital alarm clocks. The integrated circuit includes an internal presettable clock registering the time of day, an internal register storing a presettable activation time, and a gate generating an activation signal when an activation enable signal is present and the clock registers the activation time. A timer for a coffee maker also typically includes a three position switch having an "off" position, an "automatic" position, and an "on" position which enables the coffee maker regardless of the time of day.
Underwriters Laboratories has expressed concern with the operation of coffee makers in the automatic mode. About seventy fires per year have been attributed to unattended coffee makers. Presumably a fire is very unlikely for one cycle after the coffee maker has its water reservoir filled. Repeated operation with an empty water reservoir, however, increases the likelihood of having a fire. Therefore, Underwriters Laboratories is considering a requirement that an automatic timer must not repeatedly activate a coffee maker when the coffee maker is unattended.